Tomato on the WRT-54G was the all time best in my opinion.
Agreed... probably the best experience for a SOHO router+wifi. I currently use OpnSense on an N305 mini pc for my router and the separate wifi AP has it's own management interface. Works for my needs.
I tried setting it up as a test router and ran smack into their ancient kernel and iptables not supporting statistics drop mode.
Interesting, on my latest router (WRT3200ACM) I've had the opposite experience - I had to switch from OpenWRT to DD-WRT since the former was too buggy to use (couldn't get the WiFi to work reliably).